This invention relates to improvements of grinding crushers of the type each having grinder piece(s) disposed within a crushing chamber for relative rotation with respect to a casing defining the crushing chamber in which a material is ground and crushed.
In a variety of industrial fields, there have in recent years been increasing demands for ultrafine particles of less than 1 micron particle size. However, yields of such ultrafine particles of less than 1 micron particle size as obtained with the conventional mechanical grinding crushers are only around several percent of the total crushed product withdrawn through the crushing treatment, and the productivity has as well been quite poor. Looking in further detail hereinto, as shown in FIG. 6, the conventional grinding crushers are generally constructed in such manner that a casing (4') defining a crushing chamber (3') of the crusher is fixed or slowly rotatable and a driving apparatus (5') rotates grinder piece(s) (9') at relatively high speed along the casing (4') inner peripheral surface. Such being the construction, what comes primarily to mind as the measure for efficient crushing, namely to drive the grinder piece(s) (9') into strong grinding rotation with more high speed relative to the casing (4') with the material to be crushed therebetween, would not work as effectively as intended since the material would then simply move in rotation as entrained with the rotating grinder piece(s) (9') without any sufficient grinding interaction with the casing (4'), thus resulting in a drawback of practically failing to achieve the strong grinding crushing. They also have a further drawback that if the grinder piece(s) (9') is (are) rotated in high speed rotation in the intention of efficient crushing, the consequent swirling air causes to stir up the material to be crushed and thus entrains same in and along the flow, to therefore result in practically lower the grinding crushing efficiency and also in quite lacking uniformity in the product particle sizes.